Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-03-05 Thread Volodymyr Babchuk
Hi, Volodymyr Babchuk writes: > Hi Andrew, > > Andrew Cooper writes: > >> On 24/02/2021 23:58, Volodymyr Babchuk wrote: >>> And I am not mentioning x86 support there... >> >> x86 uses per-pCPU stacks, not per-vCPU stacks. >> >> Transcribing from an old thread which happened in private as part o

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-03-01 Thread George Dunlap
> On Feb 24, 2021, at 11:37 PM, Volodymyr Babchuk > wrote: > > >> Hypervisor/virt properties are different to both a kernel-only-RTOS, and >> regular usespace. This was why I gave you some specific extra scenarios >> to do latency testing with, so you could make a fair comparison of >> "extr

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-25 Thread Volodymyr Babchuk
Hi Andrew, Andrew Cooper writes: > On 24/02/2021 23:58, Volodymyr Babchuk wrote: >> And I am not mentioning x86 support there... > > x86 uses per-pCPU stacks, not per-vCPU stacks. > > Transcribing from an old thread which happened in private as part of an > XSA discussion, concerning the implic

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-24 Thread Andrew Cooper
On 24/02/2021 23:58, Volodymyr Babchuk wrote: > And I am not mentioning x86 support there... x86 uses per-pCPU stacks, not per-vCPU stacks. Transcribing from an old thread which happened in private as part of an XSA discussion, concerning the implications of trying to change this. ~Andrew -

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-24 Thread Volodymyr Babchuk
Julien Grall writes: > On Wed, 24 Feb 2021 at 20:58, Volodymyr Babchuk > wrote: >> >> >> Hi Julien, >> >> Julien Grall writes: >> >>> On 23/02/2021 12:06, Volodymyr Babchuk wrote: Hi Julien, >>> >>> Hi Volodymyr, >>> Julien Grall writes: > On 23/02/2021 02:34, Volodymyr Babchuk w

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-24 Thread Volodymyr Babchuk
Hi Andrew, Andrew Cooper writes: > On 23/02/2021 02:34, Volodymyr Babchuk wrote: >> Hello community, >> >> Subject of this cover letter is quite self-explanatory. This patch >> series implements PoC for preemption in hypervisor mode. >> >> This is the sort of follow-up to recent discussion abou

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-24 Thread Julien Grall
On Wed, 24 Feb 2021 at 20:58, Volodymyr Babchuk wrote: > > > Hi Julien, > > Julien Grall writes: > > > On 23/02/2021 12:06, Volodymyr Babchuk wrote: > >> Hi Julien, > > > > Hi Volodymyr, > > > >> Julien Grall writes: > >>> On 23/02/2021 02:34, Volodymyr Babchuk wrote: > >>> ... just rescheduling t

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-24 Thread Volodymyr Babchuk
Hi Julien, Julien Grall writes: > On 23/02/2021 12:06, Volodymyr Babchuk wrote: >> Hi Julien, > > Hi Volodymyr, > >> Julien Grall writes: >>> On 23/02/2021 02:34, Volodymyr Babchuk wrote: >>> ... just rescheduling the vCPU. It will also give the opportunity for >>> the guest to handle interrupt

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-24 Thread Andrew Cooper
On 23/02/2021 02:34, Volodymyr Babchuk wrote: > Hello community, > > Subject of this cover letter is quite self-explanatory. This patch > series implements PoC for preemption in hypervisor mode. > > This is the sort of follow-up to recent discussion about latency > ([1]). > > Motivation > =

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-24 Thread Julien Grall
On 23/02/2021 12:06, Volodymyr Babchuk wrote: Hi Julien, Hi Volodymyr, Julien Grall writes: On 23/02/2021 02:34, Volodymyr Babchuk wrote: ... just rescheduling the vCPU. It will also give the opportunity for the guest to handle interrupts. If you don't return to the guest, then risk to

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-23 Thread Volodymyr Babchuk
)[<00265458>] entry.o#guest_sync_slowpath+0xa4/0xd4 > (XEN) > (XEN) > (XEN) > (XEN) Panic on CPU 0: > (XEN) CPU0: Unexpected Trap: Data Abort > (XEN) **************** > > > On Mon, 22 Feb

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-23 Thread Stefano Stabellini
t below: > > Type: series > Message-id: 20210223023428.757694-1-volodymyr_babc...@epam.com > Subject: [RFC PATCH 00/10] Preemption in hypervisor (ARM only) > > === TEST SCRIPT BEGIN === > #!/bin/bash > sleep 10 > patchew gitlab-pipeline-check -p xen-project/patche

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-23 Thread Volodymyr Babchuk
Hi Julien, Julien Grall writes: > On 23/02/2021 02:34, Volodymyr Babchuk wrote: >> Hello community, > > Hi Volodymyr, > > Thank you for the proposal, I like the like of been able to preempt > the vCPU thread. This would make easier to implement some of the > device emulation in Xen (e.g. vGIC,

Re: [RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-23 Thread Julien Grall
On 23/02/2021 02:34, Volodymyr Babchuk wrote: Hello community, Hi Volodymyr, Thank you for the proposal, I like the like of been able to preempt the vCPU thread. This would make easier to implement some of the device emulation in Xen (e.g. vGIC, SMMU). Subject of this cover letter is

[RFC PATCH 00/10] Preemption in hypervisor (ARM only)

2021-02-22 Thread Volodymyr Babchuk
Hello community, Subject of this cover letter is quite self-explanatory. This patch series implements PoC for preemption in hypervisor mode. This is the sort of follow-up to recent discussion about latency ([1]). Motivation == It is well known that Xen is not preemptable. On other words